Fibrous web reinforced cellulosic casings



Sept. 24, 196.3 B. H. scHENK ETAL 3,104,682

FIBRoUs WEB REINFORCED cELLULosIc cAsINGs Filed July 13, 1959 4 sheets-sheet 1 INVENTORS BERNARD H. SCHENK JAMES W. MOSHER Sept. 24, 1963 B. H. scHENK ETAL FIBRoUs WEB REINFORCED cELLuLosIc cAsINGs 4 Sheets-Sheet 2 Filed July l5, 1959 11\IVENTOR: BERNARD H. SCHENK JAMES W. MOSHER AT RNEV Sept. 24, 1963 B. H. scHENK ETAL -FIBRous WEB REINFoRcED cELLuLosIc cAsINGs 4 Sheets-Sheet 3 Filed July 13, 1959 lNvENToRs A BERNARD H. SCHENK JAMES W. MOSHER ZQP ATTORAM v Sept. 24, 1963 B. H. SCHENK ETAL FIBROUS WEB REINFORCED CELLULOSIC CASINGS Filed July 13, 1959 4 Sheets-Sheet 4 INVENTORS BERNARD H. SCHENK JAMES W. MOSHER @Q'MWFR United States Patent O 3,164,682 FIBROUS WEB REINFURCED CELLULOSIC CASNGS Bernard H. Schenk, Hinsdale, and .lames W. Mosher, Chicago, lll., assignors to Union Carbide Corporation, a corporation of New York Filed July 13, 1959, Ser. No. 326,660 6 Claims. (Cl. 13S- 128) This invention relates to a fibrous web reinforced cellulosic tubing having improved strength and durability and to a method flor producing same. More particularly, it relates to such a tubing, wherein the fibrous reinforcing web is comprised of a plurality of plies or layers. l

In the manufacture of cellulosic tubing having a reinforcing web embedded there-in, a thin long-fibered single ply paper strip is curved about its longitudinal axis to form a tubing with overlapping longitudinal edges. Viscose is applied to the surface to coat and impregnato the web and also to the edges to seam and seal the tubing. The composite tubing is drawn through a regenerating bath which effects regeneration of the cellulose. The reinforced cellulose tubing is then drawn through purifying water baths, and is softened by passing through a bath containing a small percentage of a hygroscopic agent, such as glycerin. The tubing is dried by passing it in an inflated condition through a heated drying chamber. The

cellulosic casing may be reeled and stored on rolls or it may be cut into desired lengths. Such a process is disclosed in U.S. Patent No. 2,105,273.

Cellulosic tubings produced `in this manner are tough and strong. They may be used as containers or casings for sausages, meats, or other articles of food. The use of these tubings in the meat processing industry has met with a great deal of success. However, there is a continued demand for casing with greater strength to withstand the vsevere handling to which such casing is subjected. l

One method of obtaining such a tubing is 'to increase the fiber content in the web used for reinforcement. This method, however, increases the cost of producing the tubing. lFurthermore, there is some variability in the density of ber distribution in single ply web structures resulting in non-uniformity and attendant localized weak points in the nal reinforced tubing. Increasing the ber content will not of itself eliminate this nonuniformity and therefore does not proportionally increase the strength.

The weak points referred to herein are generally thin spots in the web. Also, many of the web structures used for reinforcing cellulosic sausage casings contain agglomerations and in many instances these agglomerations are thick spots adjacent to thin spots.V The nonuniformity of the reinforcing web due to the thin spots and agglomerations results in low strengt-h areas which tend to ruptur under normal processing conditions. An additional problem in the 4manufacture of such tubing for use as food casings is that of coloring the casings for sales appeal, product identification and other reasons. In' using single ply reinforcing web tubing where the web is pre-colored, it is sufficiently contiguous to the food product that there is sometimes a transfer of the coloring matter or dyes in the web to the food product itself. Consequently, such coloring matter must undergo rigid inspection and testing by the Food and Drug Administra-l ACC Patented Sept. 24, 1963 tion to assure that it is non-toxic. The contained lproduct is also discolored due to such transfer. Present processes -utilizedin the industry for coloring such casings are presing having increased strength and durability without increasing the overallfiber content.

Y `I-t is a further object to prov-ide such an improved tubing by utilizing a plurality of reinforcing webs. y

It is a further object to provide such an improved tubing in which thev longitudinal seam therein is of reduced thickness. y

It is a still further object to provide a colored fibrous web reinforced tubing wherein all portions of a precolored reinforcing web are separated from contact with objects contained 'within the tubing by at least one thickness of a web free of coloring agent.

lFurther objects and advantages will be apparent from the specifications and drawings in which:

FIGURE l` isa schematic side elevation of one type of apparatus which may be used in forming a fibrous web reinforced regenerated cellulose tubing according to the invention using two plies of said fibrous web.

IFIGURE 2 is an exaggerated transverse cross-section of a multiple ply fibrous web reinforced cellulosic tubing illustrating one type of seam formed by the overlapping edges of the multiple ply web.

:FIGURE 3 is a schematic illustration of another apparatus for .producing such reinforced cellulosic tubing wherein viscose is allowed to penetrate the reinforcing prior to the formation of the tubing.

IFlGURE 4 is a schematic illustration of still another apparatus lfor producing such tubing `wherein the reinforcing plies are axially aligned prior to formation of the tubing.

tioned in an offset manner prior to formulation .into a tube to allow for reduction in marginal-thickness.

FIGURE 6 is a cross section of the tubing made from the offset plies of FIGURE 5, showing the reduction in seam thickness.

FIGURE 7 is a detailed schematic isometric view illustrating apparatus for for-ming tubing having multiple plies of a reinforcing web wherein the plies are prelaminated.

FIGURE 8 Ishows conventional apparatus used in forming and seaming of the cellulosic tubing.

According to the invention there is provided a fibrous web reinforced cellulosic tubing having improved strength and durability which comprises a plurality of layers lof said fibrous reinforcing web seamed along their longitudinal edges to form a tube and thoroughly impregnated with a celluiosic material.

It has been found that when two layers of paper or other material lare used to form the reinforcing web, each having one-half the total basis weightV normally employed for the manufacture of reinforced cellulosic tubing that the tubing has tensile, wet tears and Mullen values greater than when the casings are reinforced with a single ply having about the same total basis weight. Thus -there is provided a reinforced cellulosic tubing with added strength and without the added cost of increasing the fiber content.

The basis weight of the web or paper as used herein is equivalent to the ream weight which is the weight in pounds of 480 sheets, size 24" x 36". The basis Weight in pounds is determined asrfollowsf Weight in grams of 91.47 sq. inches of paper X 10, corrected to 50% relative humidity. The conversion factor is taken into' account by the size of thetemplate and factorvof 10. (See ASTM Designation D646-50, Basis Weight of Paper and Paper Products, ASTM Stds. on Paper and Paper Products and Shipping Containers, September 1955.) Thus the total basis weight of the reinforcing web is directly proportional to the ltotal fiber content.

Tensile, wet tear, and Mullen values are specic ASTM tests and will be more completely designated with reference to the examples following the descriptionof the invention.

FIGURE l shows an apparatus for` preparing a multiply fibrous web reinforced cellulosic tubing according to one embodiment of the invention. In this apparatus two strips of paper 2 and 4, from rolls on individual unreelers 6 and 8, are carefully aligned and drawn over tension bar 10, over guide roll 12, subjected to curvature about their longitudinal axis around forming mandrel 17 to form a tube 14 with overlapping longitudinal margins. A strip of viscose is applied to the underlying margin as shown -at 19 in FIGURE 8 and the tubular formation 14 passes through a forming ring 16 which effects seaming the margins. Searned tube 18 then passes through a` viscose coating ring 20 which applies the viscose to the outer surface of tube 18. The coated and impregnated tube 22 passes into a coagulating and` regenerating bath, not shown since it is well known in the art, and then through yadditional purifying and glycerin baths;

FIGURE 2 is an enlarged cross sectional view taken across the completed tubular casing of FIG. l showing the reinforced cellulosic casing having two plies of reinforcing web. The two layers of the wab 2 and 4'are impregnated with cellulose 3 which has penetrated kboth layers of paper to bond .them together. The details of the four layer overlap seam are also evident in this view.

In another embodiment of thisinvention shown in FIG. 3, two rolls of lightweight paper are rewound together on a single roll to permit the unwinding of these two plies of paper `from one standard unreele-r. The method of manufacture from here on is the same as hereinbefore described. The ligure shows both rolls of paper -on one unreeler 6 leaving unreeler 6 as plies 2 and 4, passing over tension bar 10 and around guide roll 12. Furthermore, to prevent any separation of the two plies of paper in their passage from unreeler 6 to the forming ring (16 of FIGURE 1), viscose from supply head 26 can be applied to the -top ply 2 of the paper just after its departure from the unreeler 6. Application of the viscose at this point permits the viscose to penetrate into the lower ply 4 of the paper, thus minimizing relative motion between the plies 2 and 4.

Still another feature of the invention as shown in FIGURE 7 is to laminate two plies of lightweight paper, 2 and 4, with dilute viscose, regenerate the viscose to bond the plies and then dry the two-ply strip and wind it on a reel as a single sheet of laminated web. The method of manufacture of the casing from here on is the same as hereinbefore described for FIG.V l.

In this latter Iembodiment .the preferred practice is t laminate two plies of lightweight paper with viscose, regenerate the viscose with heat and thereafter wind on a reel.

trated in FIG. 4 is to utilize two rolls of lightweight paper on separate nnreelers placed well apart and brought together, from widely divergent points, at the closest possible point to the nozzle of -the forming ring. In this manner the webs are Imost readily aligned.

In FIGURE 4, one roll of lightweight paper is placed on unreeler 6 and one roll is placed on unreeler 8. The two strips of paper, 2 and 4'are drawn from unreeler 8 and 6 respectively over guide rolls 12 `and brought'together at nip rolls 15, are formed into a tube and pass through forming ring 16 where they are carefully aligned and formed into a single tube with overlapping longitudinal edges. A strip of viscose is applied to the underlying edge, and tube 14 passes through forming ring 16 which effects seaming of the edge. Seamed tube 18;

ness about its circumference, it does have a slight seamVV at the point where the fibrous web is made to overlap.k

This seam is quite evident in FIG. 2, as shown in exaggerated view therein. Another feature of this invention.

is to produce a seam of equal strength and durability but with a substantial reduction in thickness, eg., 25%. FIG.

5 illustrates the plies of paper positioned in such a manner that a portion 9 of each ply extends a distance equal to the overlap necessary Ito make the seam for the tube. In FIG. 6 it is shown that .the extent of the overlap 11 is equivalent in length to the offset distance 9 of FIG- Y URE 5. lThe advantage of so positioning the plies of paper 1 to minimize the overlap at the seam is clearly illustrated in FIGURE 6 which shows three plies of papel at the seam 13,'whereas the embodiment of FIGURE 2 requires four plies of paper at the seam to effect a joint of equivalent strength. This method of positioning the plies of paper may he used with Ithe methods and paratus of FIG. l, 3, 4 or 7.

The following examples illustrate the greater durability obtained by this invention wherein two plies of paper are used instead of a single ply and wherein the total basis weight for the two plies were substantially equal to that of the single ply.

Table Iindicates the strength values `obtained from conventional single ply. reinforced tubing. For .these tests a fibrous web of the indicated basis weight was rnade into tubing by the method described in U.S. Patent 2,105,273 fusing a viscose composition of 7% cellulose, 6% caustic and an index value of 40. l Y

'Iheindex value is the number-,of ccs. of a 10% acetic Y,

acid solution required to completely gel grams of viscose at room temperature. The test results on this tubing are shown in Taible I.

In Examples l-5 of Table II, two lplies of a paper web each having a basis weight of 6.77 were used. Each ply was fed from a separate reel. The Jwebs were removed from the reels, aligne-d as shown in FIGURE l, and formed Y into t-ubing by the method illustrated in'FIGURE 1, and

impregnated by the method shown and described in U.S.

Patent 2,105,273 using a viscose composition of 7% cel-- lulose, 6% caustic and lan index value of 40.

The test results are shown in Table II.

Table I shows the results 'obtained when fibrous tubing The examples of Table II show the results obtained 5 when a brous tubing according to this invention is used. The table clearly illustrates that tubing comprising Va multitude of layers of paper has greater durability vthan conventional single ply reinforced tubing. At the: same time, the fiber content of the cellulosic'impregnated fibrous tubing has not significantly increased.

TABLE I Wet Tears 1 (Force Wet. Tensiles 2 Mullen Values 3 Number in grams) (lbs/sq. in.) (lbs/sq. inch) Plies of Basis Wt. Sample Fibrous Each Ply,

Web lbJream Mach. Trans. Mach. Trans.

Dir., Dir., Dir. Dir. Dry Wet TAPPI TAPPI l ASTAI Designation D689-44; ASTI Stds. 1952. TAPPI-T414m- 3 ASTM: Designation D774-46; ASTLI SdS. 1955.

TABLE II Wet Tears 1 (Force Wet Tensiles 2 Mullen Values 3 Number in grams) (lbs/sq. in.) (lbs/sq. inch) Plies of Basis Wt. Sample Fibrous Each Ply,

Web lb./ream Much. Trans. Mach. Trans.

Dir., Dir., Dir. Dir. Dry Wet TAPPI TAPPI l ASTM.- Designation 13689-44; ASTM Stds. 1952. TAPPI-T4l4m-49. 2 ASTM Test D8S2-54T-C; ASTM Stds. on Plastics, October 1955, pa. 222. 3 ASTM Designation D774-46; ASTM Stds. 1955.

To further illustrate the dramatic increase in strength tubing. It may thus be seen lthat there are one or more obtained by using multiple plies of the bro-us web, each test result in Table I was divided by the total basis weight of the Webs used to show the result per unit lbasis weight. This is shown in Table III.

TABLE HI Ratio of test result/ basis wt. (T oal) [For Table I] Wet Tears Wet Tensiles Mullen Values Sample Mach. Trans. Mach Trans. Dry Wet [For Table II] A further advantage of the present invention is realized in the production of colored tubular food casings. As stated previously, when a pre-colored reinforcing web is utilized in the manufactrue of single ply reinforced tubing, difficulty is encountered due to transfer of the coloring agent to the product therein. By means of the present invention, particularly the embodiment disclosed in FIG.' 6, such transfer can be eliminated.

In producing `a colored tubing according to the present invention the -outer web or layer of reinforcing material is dyed or pigmented per se. 'Ilhe multi-ply web is then formed into a tubing and impregnated with cellulosic niaterial in the manner hereinbefore described with the colored web occupying the `outer layer of the multi-ply layers of non-colored reinforcing web between the colored web and the inside of the tubing. The separation or barrier formed by the non-colored web hasbeen found to prevent coloring agent transfer.

To completely eliminate contact of the pigmented or dyed web of the casing with the food encased therein, the manner of offsetting the layers disclosed previously in conjunction With FIGURE 6 would be used. It will 'be noted that if layer 2 of FIGURE 6 is dyed or pigmented, no contact is made between this layer land the ingredients encased therein.

The coloring of the reinforcing web may be accomplished by dyeing or pigmenting to produce the desired color, eg., TiO2 for a White casing, carbon black for a black casing. This may be done either at the time yof manufactureor subsequently. Pigmenting or dyeing of the paper is well known to those in the ar-t of paper manufacturing. y

A paper formed of hemp fibers Ibonded together with regenerated cellulose is preferred `as the fibrous reinforcing web. However, other nonwoven reinforcing webs, Such as Yoshino paper, rice paper, hemp, nylon, polyethylene terephthalate, acrylonitrile, rayon and cotton may be used. Woven fabrics such as cheesecloth, muslin, marquisette, organdy, voile and the like can also be used.

This invention, furthermore, is not limited to any given number of plies of fibrous reinforcing web. It. can be readily appreciated that the number of plies can be varied depending on the basis weight of each ply and the total overall basis Iweight of reinforcing web desired.

While the invention has been described with reference to regenerated cellulose `or viscose as the impregnating materia-l for Vthe multi-ply web, other eellulosic materiais namely, cellulose acetate, cellulose derivatives, such celiulosic ymaterial has been set forth and described as f the preferred method, internal impregna-tion by any well known method and apparatus could .be utilized. Such internal impregnation has some advantage in forming a final casing having la high `degree of smoothness which facilitates parting of the casing from the produce contained therewi-thin. However, for most applicationsexternal impregnation is suicient.

The other characteristics of the casings such as moisture vapor, smoke permeability, ilexibility and printability are substantially unchanged.

There has thus been shown 4and described a superior fibrous web reinforced cellulosic tubing having improved strength and durability and -a method for making same. These improvements are achieved Without increasing the total reinforcing fiber content and thus the cost.

While the invention has .been described with reference to certain preferred embodiments, it is to be understood that certain modifications and substitutions may be imade without departing from the spirit andscope of the invention.

The method for producing the fibrous web reinforced cellulosic casings claimed herein is claimed in a co-pending continuation-impart Serial Number 285,254, filed June 4, 1963.

What is claimed is:

1. A high strength iibrous web reinforced cellulosic food casing which comprises a plurality of layers of fibrous reinforcing yweb impregnated with a cellulosic fiber impregnating material, said plurality of layers being superimposed on one another so that at least two opposing edges :of said layers abut each other and at lleast two opposing edges thereof overlap each other forming a seam of substantially reduced sea-m thickness without a corresponding reduction in strength.

2. A high strength fibrous web reinforced cellulosic food casing which comprises a plurality of plies of fibrous reinforcing web impregnated with a cellulosic ber impregnating material, the total Ibasis weight of said plurality of plies being substantial-ly yequal to that of a conventional single ply, said plurality of plies being superimposed upon one another so that at least two opposing edges of said layers abut each other and at least two opposing edges thereof overlap each other providing a seam of equal strength and durability but with la reduction in searn thickness as compared to -a conventional overlap seam.

3. A high strength fibrous web reinforced cellulosic food casing as set forth in claim 2 wherein the cellulosic material is selected lfrom the group consisting of regenerated cellulose, cellulose acetate, and cellulose ethers.

4. A high strength fibrous web reinforced regenerated cellulose `food casing which comprises two fibrous web reinforcing strips, having a fiber content substantially equal to that of a conventional single web strip, super imposed on one another so that their edges are parallel and laterally displaced, said strips being longitudinally seamed in an overlap joint so that the outer edge ofthe resultant inner strip abuts the inner edge of the resultantv outer strip, and impregnated with regenerated cellulose to effect a joint of equivalent strength but with'a substantial reduction in thickness as compared to -a conventional overlap'seam. i

5. A high strength fibrous web reinforced regenerated cellulose food casing comprising two fibrous web Vreine forcing strips impregnated with regenerated cellulose and superimposed on one yanother so that their edges are parallel and laterally displaced, said'stri-ps being longi-y tudinally seamed in an overlap joint so that the outer edge of the resultant inner strip abuts the inner edge of the resultant outer strip, said reinforced regenerated cellulose food casing being characterized in that it has greater` strength and durability than a regenerated cellulose reinforced food casing for-med from a single strip of brous reinforcing web having a basis weight equal to the combined Iweight of the two strips.

6, A colored high strength fibrous -web reinforced cel; lulosic food casing which comprises two fibrous web reinforcing strips of equal width, one of which is colored, superimposed upon one another with their edgesparallel and 4laterally displaced, said strips lbeing longitudinally seamed in an overlap joint -to form a tube wherein the colored strip is on the exterior thereof lwith the outer edge v of the inner strip abutting the inner edge of the outer strip, said tube being impregnated with cellulosic material.

References Cited in the file of this patent UNITED STATES PATENTS 542,409 Fletcher July 9, 1895 1,313,898 Keickltefer Aug. 26, 1919 1,678,021 Preble July 24, 1928 1,846,726 lsaacks Feb. 23, 1932 1,847,269 Schur Mar. 1, 1932 1,922,767 Humphrier Aug. 15, 1933 1,961,914 Ritchter June 5, 1934 1,992,249' Snyder Feb. 26, 1935 2,014,649 Ginn Sept. 17, 1935 2,201,457 Smith et al. May 21, 19401 2,210,436 Weingand et al. Aug. 6, 1940 2,267,530 MacLachlan Dec. 23,1941 2,403,995 Peters July 16, 1946 2,623,444 Maier et al Dec. 30, 19,52Y 2,674,297 Greenwald Apr.V 6,1'1954 2,679,968 Richter June 1, 1954 2,897,087 Lawlor July 28, 1959 2,916,053 Klasing et ral. Dec. 8, 19,59... 2,916,055 Brurnbach Dec. 8, 1959 2,952,550 Parlour Sept. 13, 

2. A HIGH STRENGTH FIBROUS WEB REINFORCED CELLULOSIC FOOD CASING WHICH COMPRISES A PLURALITY OF PLIES OF FIBROUS REINFORCING WEB IMPREGNATED WITH A CELLULOSIC FIBER IMPREGNATING MATERIAL, THE TOTAL BASIS WEIGHT OF SAID PLURALITY OF PLIES BEING SUBSTANTIALLY EQUAL TO THAT OF A CONVENTIONAL SINGLE PLY, SAID PLURALITY OF PLIES BEING SUPERIMPOSED UPON ONE ANOTHER SO THAT AT LEAST TWO OPPOSING EDGES OF SAID LAYERS ABUT EACH OTHER AND AT LEAST TWO OPPOSING EDGES THEREOF OVERLAP EACH OTHER PROVIDING A SEAM OF 